In general, an oil pump including an inner rotor, an outer rotor, and multiple vanes connecting the outer periphery of the inner rotor and the inner periphery of the outer rotor is known. Such an oil pump is disclosed in Japanese Patent Laying-Open No. 2012-255439, for example.
In Japanese Patent Laying-Open No. 2012-255439, there is disclosed a pendulum-slider pump (oil pump) including an inner rotor rotationally driven, an outer rotor arranged to surround the inner rotor, configured to be rotatable outside the inner rotor, and multiple pendulums (vanes) connecting the outer periphery of the inner rotor and the inner periphery of the outer rotor. In this pendulum-slider pump described in Japanese Patent Laying-Open No. 2012-255439, a first end (tip end) of each of the pendulums is hinged to the outer periphery of the inner rotor, and a second end (base part) of each of the pendulums is fitted into a recess part of the outer rotor formed to correspond to each of the pendulums. In response to relative eccentricity between the inner rotor and the outer rotor, each of the pendulums is sequentially rotationally moved while swinging about a connecting part with the inner rotor along with the rotation of the inner rotor, and the second end of each of the pendulums is displaced to freely appear from and disappear into the recess part of the outer rotor. At this time, multiple volume chambers individually partitioned by the pendulums are sequentially repetitively deformed along with the rotation of the inner rotor, thereby providing a pumping function.
Furthermore, in order to cause the pendulums to swing (turn), an intermediate part of each of the pendulums connecting the first end and the second end is narrower than both ends (the first end and the second end). Thus, the intermediate part entering the recess part of the outer rotor is prevented from contacting with an inner wall of the recess part due to swing (inclination) of the pendulums. In addition, each of the pendulums swings, whereby both the inner rotor and the outer rotor having relative eccentricity smoothly rotate.